1. Field of the Invention
This invention relates to a method of producing semiconductor components, and more particularly to a method of producing solar energy absorbing elements fabricated from polycrystalline semiconductor material in which at least two layers of different conductivity types and a corresponding PN junction are formed in a P-or N-conducting semiconductor chip.
2. Description of the Prior Art
The use of both monocrystalline and polycrystalline silicon in the production of solar elements is known. Such elements have been incorporated into solar cells and solar batteries to transform solar energy into electrical energy (DT-OS No. 26 09 051; DT-PS No. 15 64 935; AEG Prospectus "TSG Terrestrial Solar Generators", January 1977). In fact, efficiencies of 15% have been achieved using monocrystalline silicon, as well as efficiencies of 10% using polycrystalline silicon. However, wider use of monocrystalline silicon has been precluded because of the high cost of this material.
In preparing a crystalline material for use as a solar element, a PN-junction must be produced at the surface of the crystal and can be formed by known doping methods like epitaxy, ion implantation or the simpler diffusion techniques.
With diffusion of impurities like boron, phosphorus, lithium or aluminum into silicon, experience has shown that projections of the diffusion front occur at grain locations. These projections decrease the efficiency and, in extreme cases, can lead to an inner short circuit of the PN-junction to the opposite side.